Whenever I try to unckeck HR Manager option in my personal settings and then updating my profile, the checkbox is still there and it still shows me as HR Manager even though I have assigned someone else. I have also noticed hat a bit further down in Additional Capabilities a erp_crm_manager capability is listed.
If I create another admin user and login I can uncheck the option normally. It seems that I am not able to unckeck the HR Manager role for my profile whenever I am logged in!